PLE 2019 - Biochemistry

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You want to design a synthetic oxygen transport compound that closely mimics the oxygen affinity of native hemoglobin protein. The addition of which test solution would have the greatest negative effect on the ability of your compound to bind oxygen?

Water

Carbonic acid (correct)

Bicarbonate ion

Phosphoric acid

Gout can result from a reduction in activity of which enyzme?

Glutamine phospho-transferase

PRPP

HGPRT (correct)

Glucose-6-phosphate

Methothrexate is an inhibitor of which of the following enzymes?

Ribonucleotide reductase

Thymidylate synthase

Xanthine oxidase

Dihydrofolate reductase (correct)

You are comparing metabolic byproducts from carbohydrate metabolism under aerobic and anaerobic conditions. If your cell culture condition allow for aerobic metabolism, which of the following compounds would be expected to be derived from any pyruvate generated from glycolysis?

Acetyl-CoA Signup and view all the answers

An 11-month old female patient exhibits severe developmental delay with associated macrocephaly, dysmorphic facies, hypotonia, and hepatosplenomegaly. Clouding of the corneas is not evident. A pebbly ivory-colored lesion is present over the infant's back. The activity of iduronate sulfatase in the plasma is not detectable. These symptoms are indicative of which type of mucopolysaccharidosis?

Hunter Syndrome Signup and view all the answers

A 9-year old girl is brought to her physician for an assessment of potential causes for her increased vision problems. Examination demonstrates that her eye movement is impaired and she has pigmentary retinopathy. Her physician suspects the child has Kearns-Sayre syndrome which is caused by a defect in complex II of the electron transport chain. If this diagnosis were correct, oxidation of which of the following substrates would be associated with impaired electron transfer?

Succinate Signup and view all the answers

Froilan, 25-years old, has a family history of Factor V Leiden. This factor leads to an increased risk of deep vein thrombosis owing to which of the following?

Activated form of Factor V is resistant to protein C. Signup and view all the answers

A 37-year old man presents with tophaceous deposits within the articular cartilage, synovium, tendons, tendon sheaths, pinnae, and the soft tissue on the extensor surface of the forearms. These clinical observations suggest the patient is suffering from which of the following disorders?

Gout Signup and view all the answers

A 37-year old is diagnosed with paroxysmal nocturnal hemoglobinuria. Which of the following metabolites would you expect to be increased in her urine?

Urobilinogen Signup and view all the answers

Essential fructosuria represents deficiency of which enzyme?

Fructokinase Signup and view all the answers

Activation of insulin receptors by binding of insulin results in numerous changes in the activity of other signaling proteins. Some of theses changes are increases in activity, some are decreases. Of the following enzymes, which one has an increased level of activity after insulin binds its receptor?

Glycogen synthase Signup and view all the answers

The conversion of fibrinogen to fibrin is catalzyed by which of the following?

Thrombin Signup and view all the answers

Allopurinol can be used to treat gout due to its ability to inhibit which reaction?

Xanthine to uric acid Signup and view all the answers

Many mutagenic compounds and various forms of radiation lead to mutations through the activity of an error-prone DNA repair mechanism. Which of the following causes mutations by the process of dimerization of adjacent pyrimidines?

Ultraviolet light Signup and view all the answers

The most abundant end product of nitrogen metabolism in humans is which of the following?

Glutamine Signup and view all the answers

Given that DNA polymerases are unable to synthesize DNA without a primer, what molecule serves as the primer for these enzymes during DNA replication?

A short RNA molecule Signup and view all the answers

The movement of tumor cells from their site of origin to other location within the body requires the activity of which of the following?

MMPs Signup and view all the answers

The waster nitrogen from skeletal amino acid catabolism is diverted to the liver for incorporation into urea in which of the following compounds?

Alanine Signup and view all the answers

Exogenous peripherally injected insulin differs from endogenously secreted insulin in a number of aspects, including which of the following?

Achieves a higher concentration in the periphery than in the liver, contrary to endogenous insulin Signup and view all the answers

The level of glycosylated hemoglobin is a good measure of the length of time glucose levels were elevated. Diabetic patients are most familiar with this process because they routinely measure for which of the following?

HbA1c Signup and view all the answers

Which reaction requires N5, N10-methylene-FH4 as a carbon donor?

Homocysteine to methionine Signup and view all the answers

Infants exhibiting profound metabolic ketoacidosis, muscular hypotonia, developmental retardation, and who have very large accumulations of methylmalonic acid in their blood and urine suffer from a disorder known as methylmalonic academia. This disorder results from a defect in which of the following enzymes?

Methylmalonyl-coa mutase Signup and view all the answers

Which one of the following statements about the pyruvate dehydrogenase multienzyme complex is correct?

The reaction pyruvate dehydrogenase involves decarboxylation and oxidation of pyruvate, then formation of acetyl-CoA. Signup and view all the answers

A 52-year old homeless man is noted to have numerous petechiae and suspect impaired collagen production. Given his poor dietary habits, you determine that he lacks inadequate intake of Vitamin C. For which step of collagen synthesis is ascorbic acid required?

Hydroxylation of proline residues Signup and view all the answers

One of the presenting symptoms of Vitamin B6 deficiency is dementia. This may result from an inability to synthesize serotonin, norepinephrine, histamine and GABA from their respective amino acid precursors. This is because Vitamin B6 is required for which type of reaction?

Decarboxylation Signup and view all the answers

Addition of 5-azacytidine to cultures of growing cells would be expected to result in which of the following?

Inhibition of replication Signup and view all the answers

A study on the production of an extracellular matrix by cultures of fibroblasts isolated from a melanoma is done. Histological studies demonstrates an absence of merosin. Based upon this finding, which of the following ECM components is most likely not being synthesized or processed appropriately in your cell culture system?

Laminin Signup and view all the answers

The edema observed in patients with non-calorie protein malnutrition is caused by _______.

Reduced protein synthesis in the liver. Signup and view all the answers

The incretins are hormones that are released in response to the consumption of food. Which represents one of the major effects of incretin release from intestinal epithelial cells?

Enhancement of insulin secretion from the pancrease Signup and view all the answers

Kwashiorkor can result from consuming a calorie-_____.

Deficient diet that is also deficient in protein Signup and view all the answers

You are treating a 4-year-old child who has been afflicted with recurrent infections. The child exhibits retarded development, weakness, and weight loss. Physical examination also shows absent tonsils and blood work reveals a lack of lymphocytes. These signs and symptoms are typical of severe combined immunodeficiency syndrome. Which of the following compounds would be expected to be elevated in the blood of this patients?

Deoxyadenosine Signup and view all the answers

Patients with poorly controlled Type I diabetes exhibited elevated plasma glucose concentration. In the absence of insulin, increases result due to a lack of induction of glucokinase in which of the following organs?

Liver Signup and view all the answers

Which of the following ketoacids provides in the carbon skeleton for an amino acid capable of carrying 2 atoms of nitrogen per molecule from other tissues to the liver and kidney via the blood?

Alpha-ketoglutarate Signup and view all the answers

Which of the forces or interactions play the predominant role in driving RNA secondary and tertiary structure formation?

Hydrophobic interaction Signup and view all the answers

Which of the following factors is present only in the intrinsic pathway of blood coagulation?

Factor VIII Signup and view all the answers